In recent years, with the higher integration of integrated circuits, the integrated circuits increasingly include finer cells. In general, finer cells increase the amount of leak current of integrated circuits. As the amount of leak current increases, power consumption and heat generation in an integrated circuit may increase, which may possibly damage the integrated circuit itself.
Accordingly, an amount of leak current, particularly the maximum leak current, of the integrated circuit is usually calculated while designing an integrated circuit. Specifically, a publicly known calculation method such as an SA (Simulated Annealing) method, a branch and bound method, a Monte Carlo method has been used to calculate the maximum leak current value of an integrated circuit. There is Japanese Laid-open Patent Publication No. 2005-71360 as a reference document.
However, the technology in the past has a problem of a longer calculation time for calculating the maximum amount of leak current of a highly-integrated circuit. For example, a technology using a Monte Carlo method determines the value of a signal to be input to a cell on the basis of a random number, calculates the value of the leak current corresponding to the input signal, and repeats this process. Therefore, the number of repetition of the process increases when the number of cells in an integrated circuit increases. This consumes a great amount of calculation time.